Four potentially-habitable exoplanets found 12 light years from Earth

The celestial bodies are the closest Earth-like worlds ever discovered, and, at 1.7 Earth masses, they are also the smallest on record.

A team of international astronomers have discovered four Earth-like exoplanets around a star that sits a mere 12 light-years from Earth, according to new research published in journal arXiv.

The celestial bodies are the closest Earth-like worlds ever discovered, and, at 1.7 Earth masses, they are also the smallest on record.

Researchers first detected the planets by analyzing slight wobbles in the movement of Tau Ceti, the closest known sun-like star. While the planet's wobbles are quite subtle, recent advancements have allowed scientists to study them for the first time.

"We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets," said study co-author Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz, in a statement.

Scientists believe two of the newly discovered worlds have potentially habitable atmospheres. However, all four planets are surrounded by a dense debris disk. That is problematic because it suggests the surfaces are constantly bombarded by asteroids.

Even so, the new research is important because it builds on previous attempts to disentangle stellar surface activity from gravitational anomalies. The team's algorithm has steadily improved over the past few years, and recent advancements allowed them to rule out two exoplanet candidates identified in 2013.

The researchers painstakingly improved the sensitivity of their techniques and were able to rule out two of the signals they identified in 2013 as planets. However, no matter what simulation they ran they always found rocky planets in orbit around it.

"We are slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface," said Mikko Tuomi, an astronomer at the University of Hertfordshire in England, according toUPI. "This enabled us to essentially verify the existence of the two outer, potentially habitable planets in the system."

As technology continues to improve, astronomers believe they are close to discovering even more subtle deviations in the near future. That would allow them to identify even more Earth-like planets near our world.